I've never bought anything there, but I've browsed and I don't think I've ever seen a better selection of olive oils. Going there would certainly not be a waste of time. Even if you end up not liking he place, you'll be smack dab in the middle of the Gotico, a few doors away from Caelum, a few meters away from excellent churros and La Granja. You really have nothing to lose by going there.